1. Field of the Invention
The present invention relates to a collision prediction apparatus which predictively determines a collision between a vehicle, on which the collision prediction apparatus is mounted, and an obstacle in front of the vehicle along a route of travel (hereinafter simply referred to as a “front obstacle”).
2. Description of the Related Art
Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 11-263190, there has been known an occupant protection apparatus for a vehicle which operates on the basis of results of determination as to probability of occurrence of a collision. The disclosed collision prediction apparatus acquires predetermined data items, such as position information and vehicle speed information, as information pertaining to the vehicle, and determines the probability of occurrence of a collision of the vehicle on the basis of the predetermined data items. When the probability of occurrence of a collision (hereinafter may be referred to as “collision probability”) becomes high, the predetermined data items are transmitted to a counterpart vehicle with which the vehicle may collide, to thereby secure reliable operation of an occupant protection apparatus of the counterpart vehicle.
Further, as disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 2000-142321, there has been known an occupant protection supporting apparatus which monitors the travel conditions of a vehicle and the surrounding environment, and operates on the basis of the results of monitoring. This occupant protection supporting apparatus monitors the travel conditions of the vehicle and the surrounding environment by use of a radar for detecting inter-vehicle distance, a G sensor for detecting deceleration, and an image detecting device. The occupant protection supporting apparatus processes the monitoring results so as to predict the collision probability of the vehicle. On the basis of the results of the prediction, the occupant protection supporting apparatus operates an occupant protection apparatus or a warning device, or performs communications for requesting assistance after occurrence of an accident.
Furthermore, as disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 2000-247210, there has been known an occupant protection apparatus for a vehicle which executes a predetermined operation upon reception of a collision prediction signal. This occupant protection apparatus for a vehicle checks, on the basis of a detection signal from an ultrasonic sensor, an infrared sensor, a radar, or the like, whether an obstacle is present in front of the vehicle, or whether an approaching moving object is present behind the vehicle; and determines whether the obstacle or the moving object will collide with the vehicle. In response to a front collision prediction signal or a rear collision prediction signal, which is generated when the collision probability is determined to be high, the occupant protection apparatus restricts an occupant's specific operation, to thereby ensure reliable operation of the occupant protection apparatus.
Each of the above-mentioned conventional apparatuses determines the collision probability by utilizing data output from respective detection devices as they are, as data (parameters) used to determine the collision probability, without checking whether detection is performed properly or erroneously. In some cases, the occupant protection (supporting) apparatus may erroneously recognize a collision object, depending on the shape of a road on which the vehicle travels and the environment surrounding the vehicle (e.g., a tunnel or an iron bridge). In such a case, the occupant protection (supporting) apparatus may perform a useless operation. Therefore, demand has arisen for further improvement in the accuracy of collision determination by accurately recognizing a collision object; in particular, a front obstacle present along a route of travel of a vehicle.